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- Bergquist, Daniel A., 1976-
(författare)
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Colonised Coasts : Aquaculture and Emergy Flows in the World System: Cases from Sri Lanka and the Philippines
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis conceives aquaculture as a transfer of resources within and between different parts of the world system. It is argued that due to inappropriate human-nature interactions, resources tend to flow from the South to the North, as a process of coastal colonisation. To study this resource transfer, coastal aquaculture is ap-proached from a transdisciplinary perspective, integrating natural, social, economic and spatial aspects. By combining world system theory and general systems theory, a systems view is adopted to relate aquaculture to forces of global capitalism, and analyse interactions between social and ecological processes at local and global levels. Emergy (energy memory) synthesis and participatory research methodologies were applied to two cases of aquaculture in Sri Lanka and the Philippines; monocul-ture of the black tiger prawn (Penaeus monodon) and milkfish (Chanos chanos), and polyculture of the two species together with mudcrab (Scylla serrata). The study reveals that semi-intensive shrimp monoculture in Sri Lanka generates few benefits for poor local people, and depends much on external inputs such as fry, feed and fuels, which implies negative environmental effects at local as well as global levels. Extensive polyculture in the Philippines involves more local people, and implies lower dependence on external inputs. Still, since benefits accrue mostly to elites, and mangroves are negatively affected, neither case is viable for sustainable poverty alleviation. Nevertheless, the study offers several insights into how sustainability assessment may be more transdisciplinary, and points to several factors affecting sustainability and fairness in aquaculture; the most important being mangrove con-version, local people involvement, and dependence on external inputs. Given that mangrove conversion is counteracted, extensive polyculture practices may also prove more viable in times of decreasing resources availability, and if policies are developed that favour resource efficient polyculture, and local small-scale and re-source poor farmers, instead of the global North.
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| 2. |
- Patriarca, Claudia, 1986-
(författare)
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Characterisation of natural dissolved organic matter with liquid chromatography and high resolution mass spectrometry
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dissolved organic matter (DOM) is one of the most heterogeneous and complex mixture on Earth. DOM plays a crucial role in biogeochemical processes on the global scale and it is essential to sustain and regulate the biological processes in aquatic ecosystems. DOM originates from a multitude of biological, physical and chemical transformations, leading to its phenomenal chemical diversity. In order to understand and predict its effect on the global carbon cycle, an intimate characterization at molecular level is necessary. The investigation of the extraordinary complexity of the DOM mixture represents a compelling challenge for analytical chemistry. The focus of this thesis was the development of methods for the characterization of DOM in natural waters. High resolution mass spectrometry (HRMS), was combined with high pressure liquid chromatography (HPLC) and electrospray ionization (ESI), to investigate the chemical diversity of DOM. The first study demonstrated that cutting-edge techniques (such as the Fourier-transform ion cyclotron resonance mass spectrometer - FTICR-MS), are not indispensable to disclose essential information on the DOM molecular composition, in fact the Orbitrap mass analyser is a suitable alternative for the analysis of complex natural mixtures. In the second study, the potential benefits offered by the online coupling of HPLC and HRMS instruments were explored, revealing significant advantages in terms of analysis time, achievable information and versatility of the method. The advantages of online separation were further confirmed in the third study, focused on the characterization of autochthonous labile DOM. Chromatographically resolved profiles emerged from the bulk-DOM, allowing the monitoring of labile autochthonous components in presence of heterotrophic bacteria. Despite the advantages achieved by the application of online separation, a strong limiting factor in DOM characterization is the ESI source, suitable only for the analysis of the DOM fraction susceptible to ionization. In the last study, the extent of the DOM material prone to ionization was estimated, revealing the occurrence of an extensive portion of the material resistant to routinely employed ESI approach. The full characterization of DOM is still an open challenge and the combination of multiple techniques is fundamental to unravel is extreme intricacy.
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